INTRODUCTION
Frontal bone is an intramembranous diploic bone contributing to the formation of calvarium, anterior cranial fossae, orbital roof, and upper third of maxillofacial complex. Osteomyelitis of the frontal bone is rare due to its rich vascularity from the soft-tissue envelope. Loss of scalp tissue due to trauma, spread of infection from the frontal sinus, or surgical resection may result in frontal bone osteomyelitis.[1,2] It can also occur as a major complication after neurosurgical procedures[3] or occasionally from hematogenous spread of infection.[4] Electrical burns of the scalp region resulting in osteomyelitis of calvarium are extremely rare. The authors reported a case of osteomyelitis of the frontal bone due to high-voltage electrical burn injury in a child.
CASE REPORT
An 8-year-old boy reported to our center with complaints of multiple nonhealing forehead wounds for the last 6 months. The child sustained multiple electrical burn injuries due to accidental contact with high-voltage cable while playing on the rooftop. He underwent treatment at multiple centers, and all wounds have healed except of the forehead. Clinical examination revealed two defects of exposed frontal bone on the right side [Figure 1]. The size of upper and lower defects measured 4 cm × 4 cm and 4 cm × 3 cm, respectively, and both the defects were separated by a soft-tissue pedicle. The margins were irregular, and there was granulation tissue and seropurulent discharge from the lower defect. Pus culture revealed the presence of Staphylococcus aureus microorganisms sensitive to beta-lactamase and third-generation cephalosporin group of antibiotics. The underlying bone was discolored and desiccated with no pain on probing. There were multiple areas of scar tissue contracture involving the frontal region of the scalp and extending up to the vertex. There were no focal neurological deficits. General examination revealed healed exit wound over the right elbow joint. He was diagnosed as a case of osteomyelitis of the frontal bone due to electric burn injury. Axial computed tomographic (CT) images revealed a well-defined necrotic zone surrounding the hyperdense area of the sequestrum [Figure 2].
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Figure 1: Nonhealing defects of the frontal bone following high-voltage electrical burn injury
Figure 2: Axial computed tomographic image showing osteomyelitis of the frontal bone
He was operated for sequestrectomy to debride the necrosed part of bone [Figure 3]. The soft-tissue pedicle was resected, and the margins were revised. Immediate hard-tissue reconstruction was deferred in view of chronic infection. Soft-tissue reconstruction was achieved by raising a partial thickness rotational flap pedicled on the temporal artery and rotated anteriorly to cover the defect [Figure 4]. A split-thickness skin graft was harvested from the thigh to cover the exposed pericranium at the donor site. Tissue specimen was subjected to histopathological examination that revealed areas of necrotic bone, granulation tissue along with mixed inflammatory cells. The patient recovered well with satisfactory healing and restoration of the hairline [Figure 5]. The patient had completed 2 years of follow-up period with no complications and was advised reconstruction of the residual calvarial defect.
Figure 3: Sequestrectomy of necrosed part of bone
Figure 4: Soft-tissue reconstruction of defect by partial-thickness rotational flap based on the temporal artery and coverage of donor site by split-thickness skin graft
Figure 5: Follow-up photograph showing well-healed local soft-tissue flap
DISCUSSION
Electrical injuries account for 3%–5% of all burns[5] and electrical scalp burns account for 3% of all electrical burns.[6] High-voltage electrical current, quantitatively defined as >1000 volts, is usually responsible for severe injuries to the scalp, calvarium, meninges, and brain. These injuries seldom occur in boys aged 9–15 years while playing outside on the rooftop, flying kites, and climbing trees with overhead wires.[7] The current passes from a point of entry through the body to the ground, often resulting in an entry and exit wound. The severity of injury depends on voltage, current flow, local tissue resistance, and duration of contact. The tissues such as bone are less conductive and tend to generate the most heat in accordance with Ohm's law and Joule effect. It also dissipates heat more slowly and this explains the observation that the severity of bone and deeper tissues damage often exceeds soft tissue and skin damage that cool most rapidly after injury.[5] The degree of injury, therefore, may range from partial or complete soft-tissue loss to necrosis of outer table of bone to extensive bone damage involving both the outer and inner tables.
Diagnosis of chronic osteomyelitis is based on clinical features of nonhealing wounds, nonviable bone, and imaging features of moth-eaten necrosis with radiopaque sequestra. Imaging plays an important role in the diagnosis and management of osteomyelitis. Radiographic features on plain skull radiograph are evident only after 30%–50% of bone demineralization. Magnetic resonance imaging (MRI) has emerged as the best imaging modality because of excellent anatomical detail, high sensitivity for detecting early infection, and lack of ionizing radiation. If MRI is contraindicated or unavailable, CT scan and nuclear medicine are useful alternatives. CT scan provides useful information of the extent of bony damage and intracranial involvement. Technetium-99m scan allows early assessment of the vitality of injured bone.[8]
A timely and appropriate management of scalp defects forms the cornerstone of treatment approach. An early intervention prevents desiccation, necrosis, and infection of the skull. The management involves extensive wound debridement to remove all necrotic tissues followed by soft-tissue coverage with local, distant pedicle or free flaps. The choice of flap depends on the size, location, and depth of the defect.[9] An antibiotic treatment in osteomyelitis is not effective because of inadequate blood supply and nonpenetration in the bony sequestrum. The surgical procedure performed at our center involved sequestrectomy followed by effective isolation of the anterior cranial fossa by partial thickness rotational flap pedicled on the temporal artery. Rotational flap provided good soft-tissue coverage as the defect was small with reduced donor site morbidity. The reconstruction was planned in two stages to decrease the risk of implant infection. Local scalp flaps are usually the first line of management as reconstruction of the scalp with itself is ideal. Local flaps that can be used are transposition flap, rotation flap, Orticochea flap, and V-Y-S plasty flap.[9,10] Free flaps can be considered for moderate to large defects >120 cm2 or when adequate local tissue around the defect is unavailable.[3] Various free flaps that can be utilized for scalp reconstruction include rectus abdominis flap, latissimus dorsi flap, radial forearm flap, serratus anterior flap, and omentum flap.
To conclude, electrical scalp burns are an uncommon clinical presentation and skull osteomyelitis is a rare serious complication. An adequate clinical and radiological assessment, understanding of the mechanism of electrical burn injury, and early and aggressive surgical intervention followed by soft-tissue flap reconstruction are of paramount importance to achieve satisfactory cosmetic and functional outcomes.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Acknowledgments
This study was supported by the National Natural Science Foundation of China (81601612) and the Jiangsu Provincial Key Research and Development Program (CN) (BE 2015613, BE 2016763, and BE2019608). We thank Dr. Xu Yan and Dr. Zhou Jin for their assistance in performing the language modification and data analysis.
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